This invention relates to aquarium filtration, and more particularly to improvements in the biological filtration of aquarium water. In addition, this invention relates to an aerobic chamber which is used in conjunction with a primary aquarium filter to enhance the removal of wastes from the aquarium water and which discharges the aquarium water directly into the aquarium.
Whenever aquatic animals are to be maintained within an aquarium environment, the quality of the water in which they live must be maintained at a suitable level. In addition to properly controlling the temperature, dissolved oxygen and other water qualities, the toxic material content of the water must be maintained at a sufficiently low level to prevent harm to the fish.
The main source of contaminants within an aquarium are the aquatic animals themselves. The metabolic waste of the aquatic animals is stored within the aquarium. In high concentrations, these waste products become toxic to the same animals that produce them.
To combat the problem of toxic waste build-up, three types of filtration approaches are generally utilized. One approach is physical filtration wherein the suspended waste material is physically trapped by mechanical filters. The filters utilize filtration material in the form of particles of gravel, or fluffy masses of synthetic resin fibers. Sand or gravel beds are well known materials which are also used in undergravel type of filters performing such mechanical filtration.
The second well known type of filtration is chemical filtration which relates to the removal of or deactivation of mostly organics and any substance containing the element carbon. Activated carbon and ion exchange resins are commonly used materials. While the above forms of filtration are well known and frequently utilized, they are generally insufficient for purifying the water and eliminating some of the common known toxic waste products of the aquatic animals themselves.
The third type of filtration which is probably the most important and yet often least utilized, is that of biological filtration. Such biological filtration is accomplished by means of living organisms, primarily bacteria. The presence of these biologically active bacteria in an aquarium is essential, since they serve to rid the tank of toxic ammonia.
Examples of aquarium filters which provide physical, chemical and aerobic filtration are described in U.S. Pat. Nos. 4,512,885, 4,622,148 and 4,714,547 assigned to the assignee of the present invention.
Ammonia is a highly toxic substance harmful to many aquatic animals even if present in very low concentrations. Ammonia toxicity is pH sensitive. The higher the pH, the more toxic the ammonia becomes. Since marine aquariums generally maintain a higher pH than their fresh water counterparts, ammonia levels are of greater concern in the salt water aquarium. However, even in fresh water aquarium tanks ammonia can build up to high levels and cause toxicity to the water.
Ammonia is generated by the animals themselves which excrete ammonia directly. Additionally, ammonia is the end product of decaying organic matter such as uneaten food, dead animals, and feces. The ammonia is removed from the aquarium through biological filtration by a process called "nitrification". Nitrification is a two step process which requires two different types of bacteria to perform each step. These two types of bacteria are referred to as nitrifiers or nitrifying bacteria.
The first step in this sequence is performed by bacteria of the type Nitrosomonas. These bacteria remove ammonia from the water and, through biological oxidation, convert it to a different substance, nitrite. While nitrite is generally less toxic than ammonia, the removal of ammonia still does not provide adequate purification of the water. However, a different group of bacteria, the Nitrobacter bacteria quickly act on the nitrite and convert it further to nitrate, which is harmless to the aquatic inhabitants.
Both of these types of bacteria are of the aerobic form. However, even anaerobic bacteria are useful in reducing the ammonia, although they produce different end products, some of which are toxic to aquatic life. By maintaining an adequate supply of oxygen to the aquarium, the anaerobic bacteria can be kept in check and adequate aerobic bacteria are provided.
The aerobic nitrifying bacteria have two basic requirements to carry out their functions. The first is the need for adequate oxygen concentrations. The second is that they require a place to attach themselves.
Prior art filters which provided enhanced aerobic filtration were complex, large and expensive devices. These filters referred to as wet/dry filters include a chamber providing mechanical filtration, being the wet part, and an aerobic chamber being the dry part because of the large amounts of oxygen in the aerobic chamber. Typically, the prior art wet/dry filters require two pumps, one to draw aquarium water into the primary filter and one to pump the aerobically filtered water back into the aquarium. In addition the prior art filters required a balance between the input to the filter and the output of the filter to avoid either overflowing the aerobic chamber or not having sufficient water for the pump returning the water to the aquarium to operate efficiently. It also required collection of the water dripping through the aerobic chamber to provide an adequate amount to support the return pumping of the water back to the aquarium.
While previous filters have in fact provided primary and aerobic filtration, still further enhancement and improvement of aerobic filtration is desirable. These enhancements and improvements would be particularly beneficial if the aerobic filtration supplements the filtration of the primary filter which provides physical filtration together with chemical filtration, and discharges directly into the aquarium, thereby eliminating the need for multiple pumps and balancing the output of the primary filter with the output of the aerobic filter, and permitting a less costly and simplified aerobic filter arrangement. In addition, the aerobic filters should have large surface areas for the aerobic nitrifying bacteria to attach themselves to and have sufficient oxygen concentrations to permit optimum growth of the bacteria.